<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      const v1 = "hello";
      const v2 = "jack";
      // const v3;
      const v3 = null;
      v1 = null; // v1 所占用的内存被释放
    </script>
  </body>
</html>
